Legionella Risk Assessment What Every Property Owner Should Know

Legionella is a type of bacteria that can pose a serious health risk if not properly managed. It thrives in water systems and can cause Legionnaires’ disease, a severe form of pneumonia. As a property owner, understanding the importance of Legionella risk assessment is crucial to ensuring the safety of occupants and complying with legal requirements. This guide will provide everything you need to know about Legionella risk assessment, including its importance, legal obligations, risk factors, and steps to take for effective control.

What is Legionella?

Legionella is a bacteria found naturally in freshwater environments such as lakes and rivers. However, it becomes a problem when it enters man-made water systems, such as:

Hot and cold water systems
Cooling towers
Spa pools and hot tubs
Air conditioning units
Water tanks and storage facilities

The bacteria thrive in warm water (20-45°C), especially when stagnant, and can multiply rapidly if the conditions are right. When water containing Legionella bacteria is aerosolized (through showers, taps, or air conditioning systems), people can inhale the bacteria, leading to Legionnaires’ disease.

Why is Legionella Risk Assessment Important?

A Legionella risk assessment is the process of identifying and controlling the risk of Legionella bacteria in a water system. It is essential because

Health and Safety Compliance: Property owners and landlords are legally required to assess and manage Legionella risks.
Prevention of Legionnaires’ Disease: Regular assessments help prevent outbreaks that can lead to severe illness and even fatalities.
Legal Liability: Failure to conduct a Legionella risk assessment can result in prosecution, fines, and reputational damage.

Legal Requirements for Legionella Risk Assessment in the UK

In the UK, property owners must comply with legislation related to Legionella risk assessment. The key regulations include:

Health and Safety at Work Act 1974
This act places a duty on employers, landlords, and property owners to ensure the health and safety of their tenants, employees, and visitors. This includes managing Legionella risks in water systems.
Control of Substances Hazardous to Health (COSHH) Regulations 2002
COSHH requires employers and landlords to assess and control the risks associated with hazardous substances, including Legionella bacteria.
Approved Code of Practice (ACoP) L8 ACoP L8
provides guidance on controlling Legionella in water systems. It sets out the legal duties and best practices for risk assessment, monitoring, and control.
Landlord Responsibilities
Landlords of both residential and commercial properties must conduct a Legionella risk assessment to protect tenants from potential exposure. Although there is no specific legal requirement for landlords to obtain a certificate, they must demonstrate that they have taken reasonable steps to assess and control the risk.

Who Needs a Legionella Risk Assessment?

A Legionella risk assessment is necessary for:

Landlords of residential and commercial properties
Employers responsible for workplace safety
Facilities managers in public buildings
Operators of hotels, care homes, and hospitals

Essentially, anyone responsible for a water system that could pose a Legionella risk should conduct an assessment.

Common Risk Factors for Legionella Growth

Several factors can contribute to Legionella growth in a water system, including:

Water Temperature
Legionella bacteria multiply rapidly in water temperatures between 20°C and 45°C. Keeping hot water above 60°C and cold water below 20°C can help prevent bacterial growth.
Stagnant Water
Stagnation allows bacteria to multiply. Unused taps, dead-end pipes, and low water flow areas should be addressed in a risk assessment.
Biofilm and Scale Buildup
Limescale, rust, and biofilm can provide a surface for Legionella to grow. Regular cleaning and maintenance of water systems are essential.
Aerosol Generation
Showers, cooling towers, and air conditioning systems that create fine water droplets increase the risk of inhalation and Legionnaires’ disease.
Contaminated Water Sources
Legionella can enter a water system from a contaminated mains supply or through maintenance work. Proper filtration and disinfection measures can help reduce this risk.

Steps to Conduct a Legionella Risk Assessment

A Legionella risk assessment should be thorough and conducted by a competent person. The key steps include:

1. Identify Water Systems
Locate all water systems in the property, including storage tanks, pipes, and outlets.

2. Assess Potential Risks
Evaluate areas where Legionella bacteria could grow, such as water temperatures, stagnant water, and biofilm buildup.

3. Implement Control Measures
Based on the findings, apply measures such as:

Keeping water temperatures outside the Legionella risk range
Flushing unused outlets regularly
Cleaning and descaling pipes and tanks
Installing water treatment systems (e.g., chlorination)

4. Record Findings and Actions Taken
Maintain a record of the assessment, including identified risks and implemented control measures. This documentation is crucial for legal compliance.

5. Review and Update Regularly
A Legionella risk assessment is not a one-time task. It should be reviewed periodically and updated when there are changes to the water system or property usage.

Control Measures for Legionella Prevention

Once a risk assessment is completed, property owners should implement the following control measures:

1. Temperature Control

Keep hot water at 60°C or higher
Keep cold water below 20°C
Regularly check water temperatures

2. Regular Flushing
Flush unused taps, showers, and water outlets at least once a week to prevent stagnation.

3. Water System Cleaning
Descale and disinfect water tanks, pipes, and cooling systems regularly.

4. Water Treatment
Use chemical treatments such as chlorine or biocides to control bacteria in large water systems.

5. Monitoring and Maintenance
Schedule routine inspections and maintenance to ensure compliance with risk assessment findings.

What Happens if Legionella is Found?

If Legionella bacteria are detected in a water system, immediate action is necessary. This may include:

Shutting down affected areas until the risk is mitigated
Disinfecting the system with appropriate chemical treatments
Reviewing and updating the risk assessment
Informing relevant authorities if an outbreak occurs

Consequences of Non-Compliance

Failure to conduct a Legionella risk assessment can lead to:

Health risks: Increased risk of Legionnaires’ disease outbreaks
Legal penalties: Fines, prosecution, and even imprisonment under health and safety laws
Reputational damage: Loss of trust from tenants, employees, and customers

Hiring a Professional Legionella Risk Assessor

While property owners can conduct basic risk assessments, hiring a professional can provide a more thorough evaluation. Benefits of professional assessments include:

Expert knowledge of regulations and compliance requirements
Use of advanced testing and monitoring techniques
Detailed reports and recommendations for control measures

A Legionella risk assessment is a critical process that every property owner must undertake to ensure the safety of occupants and compliance with UK regulations. By identifying potential risks, implementing effective control measures, and maintaining regular monitoring, property owners can prevent Legionnaires’ disease and avoid legal consequences.

If you’re responsible for a water system, take proactive steps today—schedule a Legionella risk assessment and protect your property from this hidden danger.